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Subject: Re: Size related to slowness?
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From: David Moore <dmoore@ucsd.edu>
Date: 23 Apr 1997 09:12:00 -0700
In-Reply-To: Hrvoje Niksic's message of 23 Apr 1997 08:23:55 +0200
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Hrvoje Niksic <hniksic@srce.hr> writes:

> BTW, it should be feasable to see whether this is so by profiling the
> symbol table lookups in four cases:
> 
> 1) XEmacs, `-q'
> 2) XEmacs, with lots of packages loaded
> 3) GNU Emacs, `-q'
> 4) GNU Emacs, with lots of packages loaded
> 
> I'm sure it would give more insight into the matter.

Unlikely.  The biggest cost function (typically) on straight lisp code
store_symval_forwarding (when inlined), which tends to suggest that our
magic lookups are costing more than they should.  It gave me a headache
when I last looked at it.

The way you profile something is to profile it.  It's a busy week, but
I'll try to mail out my patches to enable -pg profiling, so you can
begin to see for yourselves where the costs are.  But if you're going to 
look at these things, it might be wise to think about what profiling
tells you and what it doesn't tell you.  It's not a magical thing, where 
we wave the dead chicken over emacs and suddenly learn exactly what to
do.

Comparing anything that's been totally redesigned to gnu emacs just
isn't worth the effort.  Find the real bottlenecks in xemacs and attack
those.  Don't be led astray by what the profiler says either (or at
least understand how it lies).

